Slow Magnetic Relaxation in Lanthanide Complexes with Chelating Nitronyl Nitroxide Radical

Two rare-earth radical complexes [Ln(hfac)₃NIT-2Py]·0.5C₇H₁₆ [Ln = Tb (1), Dy (2)] have been synthesized and characterized structurally as well as magnetically. Both complexes are isomorphous, in which the NIT-2Py radical is coordinated to the Ln^III ion in a chelating manner. Magnetic studies reveal that complex 1 shows a frequency-dependent, alternating-current magnetic susceptibility typical of a single-molecule magnet, whereas slow magnetic relaxation is observed in 2 under an applied direct-current field.